U.S. patent number 5,847,802 [Application Number 08/892,466] was granted by the patent office on 1998-12-08 for concentric annular ring lens designs for astigmatic presbyopes.
This patent grant is currently assigned to Johnson & Johnson Vision Products, Inc.. Invention is credited to Edgar V. Menezes, Jeffrey H. Roffman.
United States Patent |
5,847,802 |
Menezes , et al. |
December 8, 1998 |
Concentric annular ring lens designs for astigmatic presbyopes
Abstract
Concentric lens designs are disclosed for astigmatic presbyopes
which comprise at least one surface which has a circular central
portion and a plurality of concentric annular rings with at least
three separate optical powers corresponding to a prescription for a
patient and corresponding to 1) a basic distance spherical
prescription Rx, 2) a near add spherical prescription Rx, and 3) a
spherical prescription corresponding to the full, or preferably a
fraction of the, cylindrical prescription Rx. An astigmatic
presbyopic prescription contains an astigmatic correction, normally
in the nature of a cylindrical prescription which specifies both
the cylindrical optical power and the orientation of the
cylindrical axis. The cylindrical prescription is taken into
account in the design of the lens, but not with a cylindrical
optical surface. Instead, the present invention recognizes that the
brain can effectively discriminate between separate competing
images by accepting an in-focus image and rejecting an out-of-focus
image. Accordingly, a portion of the lens is provided with a
spherical surface corresponding to the cylindrical prescription, or
more preferably a fraction of the full cylindrical prescription,
and the brain is relied upon to discriminate and accept an in-focus
image to compensate for the patient's astigmatism.
Inventors: |
Menezes; Edgar V.
(Jacksonville, FL), Roffman; Jeffrey H. (Jacksonville,
FL) |
Assignee: |
Johnson & Johnson Vision
Products, Inc. (Jacksonville, FL)
|
Family
ID: |
23721757 |
Appl.
No.: |
08/892,466 |
Filed: |
July 14, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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433844 |
May 4, 1995 |
|
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Current U.S.
Class: |
351/159.12;
623/6.28; 351/159.07 |
Current CPC
Class: |
G02C
7/044 (20130101); G02C 7/042 (20130101); G02C
7/06 (20130101) |
Current International
Class: |
G02C
7/04 (20060101); G02C 7/06 (20060101); G02C
007/04 () |
Field of
Search: |
;351/161,168,169,171,176,177 ;623/6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Epps; Georgia
Assistant Examiner: Schwartz; Jordan M.
Attorney, Agent or Firm: Kiernan; Anne B.
Parent Case Text
This is a continuation of application Ser. No. 08/433,844, filed
May 4, 1995, now abandoned.
Claims
What is claimed is:
1. A multifocus, concentric annular ring lens for astigmatic
presbyopes, said lens comprising:
a front surface and an opposite back surface, wherein one of the
front and back surfaces defines a central area comprising a
circular disc having a surface corresponding to a basic
prescription distance optical power of an astigmatic presbyope;
and
a plurality of annular rings surrounding the central area and
comprising at least one first annular ring corresponding to a near
optical power prescription of the presbyope and at least one
circumferentially invariable second annular ring corresponding to a
cylindrical optical power prescription of the presbyope, said
multifocus concentric annular ring lens eliminating the requirement
for cylindrical axis stabilization.
2. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 1, wherein the circular disc defines
a spheric curve.
3. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 2 wherein at least one of the
annular rings defines a spheric curve.
4. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 1, wherein the circular disc defines
an aspheric curve.
5. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 4, wherein at least one of the
annular rings defines a spheric curve.
6. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the second annular ring
corresponds to the full cylindrical power prescription.
7. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the second annular ring
corresponds to a fraction of the full cylindrical power
prescription.
8. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the plurality of annular
rings also comprise at least one third annular ring corresponding
to the basic prescription distance optical power of the
presbyope.
9. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 8, wherein the plurality of annular
rings comprise alternating ones of said first, second and third
annular rings.
10. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the innermost annular
ring is one of said first annular rings and the second innermost
annular ring is one of said second annular rings.
11. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in 10, further comprising at least one third
annular ring corresponding to the basic prescription distance
optical power of the presbyope wherein the third innermost annular
ring is one of said third annular rings.
12. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 8, wherein the innermost annular
ring is one of said first annular rings and the second innermost
annular ring is one of said third annular rings.
13. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 12, wherein the third innermost
annular ring is one of said second annular rings.
14. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the lens comprises a
contact lens to be worn on the cornea of the eye.
15. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 14, wherein the contact lens
comprises a soft hydrogel contact lens.
16. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the lens comprises an
intraocular lens.
17. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the widths of individual
annular rings are different to generate a power profile which
varies to generate different ratios of distance optical power to
cylindrical correction optical power and distance optical power to
near optical power.
18. A multifocus, concentric annular ring lens for astigmatic
presbyopes as claimed in claim 3, wherein the central area and the
plurality of annular rings are formed on the back surface of the
lens to minimize flare and glare problems.
19. A method of designing a multifocus, concentric annular ring
lens for astigmatic presbyopes comprising the steps of:
selecting a lens comprising a front surface and an opposite back
surface, wherein one of the front and back surfaces defines a
central area comprising a circular disc having a surface
corresponding to a basic prescription distance optical power of an
astigmatic presbyope, said lens further comprising a plurality of
annular rings surrounding the central area and comprising at least
one first annular ring corresponding to a near optical power
prescription of the presbyope and at least one circumferentially
invariable second annular ring corresponding to a cylindrical
optical power prescription of the presbyope, said multifocus
concentric annular ring lens eliminating the requirement for
cylindrical axis stabilization;
performing an in vivo image quality analysis, of the lens on the
eye to measure residual aberrations; and
reducing the measured residual aberrations by redesigning the lens
to improve visual acuity and performance.
20. A method of designing a multifocus concentric annular ring lens
as claimed in claim 19, wherein redesigning the lens includes
aspherizing the surface opposite the surface defining the central
area and the plurality of annular rings.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to concentric annular ring
lens designs for astigmatic presbyopes. More particularly, the
subject invention pertains to such concentric annular ring lens
designs wherein at least one surface of the lens has a circular
central portion and a plurality of annular rings with at least
three separate spherical optical powers corresponding to a
prescription for the astigmatic presbyopic patient. The three
separate spherical optical powers correspond to 1) a basic distance
spherical prescription Rx, 2) a near add spherical prescription Rx,
and 3) a spherical prescription corresponding to the full, or
preferably a fraction of the, cylindrical prescription Rx.
2. Discussion of the Prior Art
The present invention pertains to ophthalmic lenses, and in
particular to contact lenses such as soft hydrogel contact lenses,
and intraocular lenses, designed particularly for astigmatic
presbyopes.
It is well known that as an individual ages, the eye is less able
to accommodate, i.e. bend the natural lens in the eye, in order to
focus on objects that are relatively near to the observer. This
condition is referred to as presbyopia, and presbyopes have in the
past relied upon spectacles or other lenses having a number of
different regions with different optical powers to which the wearer
can shift his vision in order to find the appropriate optical power
for the object or objects upon which the observer wishes to
focus.
Similarly, for a person who has had the natural lens of the eye
removed because of a cataract condition and an intraocular lens
inserted as a replacement, the ability to adjust the lens
(accommodate) to the distance of the object being viewed is totally
absent. In this case, the lens provided is usually set at a single
infinite distance focal power, and spectacles are worn to provide
the additional positive optical power needed for in-focus closer
vision. For such a patient, a functional multifocal lens would be
particularly useful.
It is known that for astigmatic subjects, the astigmatic eye forms
an image which contains three main regions:
1. The spherical power focuses as a line;
2. The cylindrical power also focuses as a line, perpendicular to
the spherical image line;
3. In between the two, a circular image is formed, known as the
"circle of least confusion."
It is also known in the art that under certain circumstances the
brain can effectively discriminate between separate competing
images by accepting an in-focus image and rejecting an out-of-focus
image.
Toric contact lenses are normally prescribed for astigmatic
patients with either corneal or lenticular astigmatism, and have a
cylindrical optical surface/power which is used to correct for
astigmatism in a wearer. Statistically, astigmatism usually occurs
in people primarily around either the horizontal axis or the
vertical axis, but also at varying axial locations with respect
thereto. In the prior art a separate type of toric contact lens is
required for each different toric optical power and also for each
different orientation of the toric cylindrical axis of the contact
lens, which are required to accommodate different patients with
differing amounts of astigmatism along different axes.
Accordingly, an inventory of toric contact lenses, or plastic
molding parts for molding the toric contact lenses, include a
number of different combinations of toric axis location and toric
optical power. One significant advantage of the present invention
is a resultant substantial reduction in the number of stock keeping
units maintained in inventory (different possible prescriptions
maintained in inventory).
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to
provide concentric lens designs for astigmatic presbyopes.
Another object of the present invention is the provision of
concentric annular ring lens designs for astigmatic presbyopes
which results in a substantial reduction in the number of stock
keeping units maintained in inventory.
A further object of the subject invention is the provision of
concentric lens designs for astigmatic presbyopes which comprise at
least one surface which has a circular central portion and a
plurality of concentric annular rings with at least three separate
optical powers corresponding to a prescription for a patient and
corresponding to 1) a basic distance spherical prescription Rx, 2)
a near add spherical prescription Rx, and 3) a spherical
prescription corresponding to the full, or preferably a fraction of
the, cylindrical prescription Rx.
A presbyope requires a lens with a basic distance spherical
prescription for focusing on distant objects and a near spherical
prescription (add) for focusing on near objects. In addition
thereto, an astigmatic presbyope requires an astigmatic correction,
normally in the nature of a cylindrical prescription which
specifies both the cylindrical optical power and the orientation of
the cylindrical axis. The present invention takes the cylindrical
prescription into account in the design of the lens, but does not
use a cylindrical optical surface. Instead, the present invention
recognizes that the brain can effectively discriminate between
separate competing images by accepting an in-focus image and
rejecting an out-of-focus image. Accordingly, the present invention
provides a portion of the lens with a spherical surface
corresponding to the cylindrical prescription, or more preferably a
fraction of the full cylindrical prescription, and relies upon the
brain to discriminate and accept an in-focus image to compensate
for the patient's astigmatism. The spherical surface corresponding
to the cylindrical prescription provides a lens with an improved
depth-of-field for low cylindrical astigmats.
The present invention is directed to concentric lens designs for
astigmatic presbyopes which provide:
(i) the ability to address the visual prescription requirements of
approximately 25% of the vision correction market;
(ii) the ability to provide high volume/low cost contact lenses
with a minimal number of stock keeping units in inventory,
comparable to current spherical contact lenses;
(iii) the ability to eliminate the requirement for cylindrical axis
stabilization features for astigmatic patents, thereby providing
for greater patient comfort and east of fit; and
(iv) the ability to provide lens designs that are finely tunable to
the individual needs of a patient.
In accordance with the teachings herein, the present invention
provides a multifocus, concentric annular ring lens for astigmatic
presbyopes, wherein one of the front and back surfaces of the lens
defines a central area comprising a circular disc having a
spherical surface corresponding to a basic prescription distance
optical power. A plurality of annular rings surround the central
area and comprise at least one spherical near optical power annular
ring and at least one spherical optical power annular ring which
corresponds to the cylindrical optical power prescription of the
patient, to provide visual acuity for astigmatic presbyopes.
In greater detail, the spherical optical power annular ring which
corresponds to the cylindrical optical power prescription of the
patient can correspond to the full cylindrical power prescription
or a fraction of the full cylindrical power prescription. The
plurality of annular rings also comprise at least one spherical
distance optical power annular ring. The plurality of annular rings
can comprise alternating spherical near optical power annular
rings, spherical distance optical power annular rings, and
spherical optical power annular rings which correspond to the
cylindrical optical power prescription of the patient. The
innermost annular ring is preferably a spherical near optical power
annular ring, and the second innermost annular ring can be a
spherical optical power annular ring which corresponds to the
cylindrical optical power prescription of the patient, and the
third innermost annular ring is a spherical distance optical power
annular ring. Alternatively, the second innermost annular ring is a
spherical distance optical power annular ring, and the third
innermost annular ring is a spherical optical power annular ring
which corresponds to the cylindrical optical power prescription of
the patient. The lens can comprise a contact lens to be worn on the
cornea of the eye, such as a soft hydrogel contact lens, or an
intraocular lens. For a contact lens, the central area and the
plurality of annular rings are preferably formed on the back
surface of the lens to minimize flare and glare problems. Moreover,
the widths of the individual annular rings can be different to
generate a power profile which varies to generate different ratios
of distance optical power to cylindrical correction optical power
and distance optical power to near optical power.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing objects and advantages of the present invention for
concentric lens designs for astigmatic presbyopes may be more
readily understood by one skilled in the art with reference being
had to the following detailed description of several preferred
embodiments thereof, taken in conjunction with the accompanying
drawings wherein like elements are designated by identical
reference numerals throughout the several views, and in which:
FIG. 1 is a plan view of the back surface of one designed
embodiment of a preferred type of contact lens pursuant to the
teachings of the present invention which has a central area with a
circular disc having a basic prescription Rx spherical distance
optical power, surrounded by a plurality of alternating concentric
spherical near optical power, concentric spherical distance optical
power, and spherical annular rings which correspond to the
cylindrical power prescription of the patient.
DETAILED DESCRIPTION OF THE DRAWINGS
The present invention provides a lens design for astigmatic
presbyopes. A presbyope requires a lens with a basic distance
spherical prescription for focusing on distant objects and a near
spherical prescription (add) for focusing on near objects. In
addition thereto, an astigmatic presbyope requires an astigmatic
correction, normally in the nature of a cylindrical prescription
which specifies both the cylindrical optical power and the
orientation of the cylindrical axis. The present invention takes
the cylindrical prescription into account in the design of the
lens, but does not use a cylindrical optical surface. Instead, the
present invention recognizes that the brain can effectively
discriminate between separate competing images by accepting an
in-focus image and rejecting an out-of-focus image. Accordingly,
the present invention provides a portion of the lens with a
spherical surface having the cylindrical optical power
prescription, or more preferably a fraction of the full cylindrical
prescription, and relies upon the brain to discriminate and accept
an in-focus image to compensate for the patient's astigmatism. The
spherical surface which corresponds to the cylindrical prescription
provides a lens with an improved depth-of-field for low cylindrical
astigmats.
Referring to the drawings in detail, FIG. 1 is a plan view of the
back surface of one designed embodiment of a preferred type of
contact lens 10 pursuant to the teachings of the present invention.
The lens 10 has a central area with a circular disc 12 containing a
basic prescription Rx spherical distance optical power which is
surrounded by a plurality of alternating concentric annular rings
14, 16, 18, 20 and 22. The plurality of alternating concentric
annular rings includes a spherical near optical power annular ring
14, spherical distance optical power annular rings 18 and 22, and
spherical power annular rings 16 and 20 which correspond to the
cylindrical power prescription of the patient. The spherical power
which corresponds to the cylindrical power prescription of the
patient can be the sum of the basic spherical distance optical
power and the cylindrical prescription optical power or the sum of
the basic spherical distance optical power and a portion (25% to
100%) of the cylindrical prescription optical power.
Preferably the back surface of the lens is provided with the
multiplicity of concentric rings shown in FIG. 1, although the
front surface is also suitable, particularly in intraocular
lenses.
For example, consider an astigmatic presbyopic patient prescription
of: -2.00/-1.00.times.180 with 1.25 D add. In this prescription,
-2.00 diopters is the basic spherical distance prescription Rx,
-1.00 diopters is the astigmatic cylindrical optical power
prescription Rx correction and 180 specifies a horizontal
cylindrical axis, and 1.25 diopters is the near spherical
prescription Rx add. In this exemplary embodiment, the powers
chosen for the concentric annular rings can be SPHERE (S)=-2.00 D
(diopters), CYLINDER (C)=-3.00 D (which is the sum of the spherical
distance prescription Rx -2.00 and the cylindrical prescription Rx
-1.00) and NEAR (N)=-0.75 D (which is the sum of the spherical
distance prescription Rx -2.00 and the near spherical prescription
Rx add +1.25).
Some patients may not require the full cylindrical and add powers
in these designs. For these cases, the cylindrical and near powers
can be made a fraction (preferably 50%) of the full cylinder or add
power. The cylindrical power can be the full cylindrical difference
or any portion thereof, ranging from 25% to 100% of the full
refractive cylindrical power. The specified position for the
cylindrical axis is ignored since a spherical surface is
substituted therefor. It is not expected that the visual acuity of
the patient will deteriorate significantly for low cylindrical
astigmats because of the increased depth-of-focus provided by the
concentric annular ring designs of the present invention.
Alternately, the near add optical power could be a non-constant
function across the concentric annular rings.
The present invention functions by alternating spherical power with
cylindrical equivalent spherical power in such a way as to provide
adequate levels of images from both optical powers to the retina of
the observer.
In general, the powers in the zones may be arranged in a manner
determined to be suitable to the visual needs of the patient. Some
examples of possible arrangements are shown below, wherein the
central disc 12 is listed as the first ring:
______________________________________ ARRANGEMENT OF RINGS FROM %
OF RINGS FOR CENTER OF LENS # RINGS SPHERE CYLINDER NEAR
______________________________________ SNCS 4 50 25 25 SNSCS 5 60
20 20 SNCSCNS 7 43 29 29 SNSCSNSCSNS 11 55 18 27 SNCNSNCNSNCNS 13
31 23 46 SNCNSCSCSNCNS 13 38 31 31
______________________________________ (Where S = SPHERE, C =
CYLINDER AND N = NEAR)
In alternative embodiments, the positions of C and N can be
reversed, and clearly, many other combinations than those
specifically shown are possible.
The combined areas of the center spherical disc 12 and the
surrounding annular rings 14 through 22 comprise the active optical
area of the lens, which is surrounded by a lenticular (nonoptical)
area 24 which is beveled at its outer circumference to an outer
circumferential edge 26 of the lens.
The lens can be a contact lens to be worn on the cornea of the eye,
such as a soft hydrogel contact lens, or can be an intraocular
lens. The central area and the plurality of annular rings are
preferably formed on the rear surface of a contact lens to minimize
flare and glare problems.
A person's pupil size is a function which is dependent upon light
intensity, and is an important parameter in the design of
ophthalmic lenses, particularly contact lenses and intraocular
lenses.
Moreover, the widths of the individual annular rings can be
different to adjust the area of the optic zone devoted to each
power, to generate a power profile which varies to generate
different ratios of distance optical power to cylindrical
correction and distance optical power to near optical power.
Moreover, in order to provide a depth-of-focus effect, asphericity
can be incorporated into either of the S, C and/or N rings, or the
surface not containing the concentric rings can be made
aspherical.
Moreover, ocular in vivo image quality measurement devices can be
used to optimize the ocular image quality in the concentric annular
ring lens designs to produce even more improved designs. This is
accomplished by using an in vivo image quality measurement device
to measure and decrease the sum of the aberrations of a first
design of a lens on the patient's eye to measure residual
aberrations, and then redesigning the lens to reduce the measured
residual aberrations and improve visual acuity and performance. The
redesign of the lens can include aspherizing the surface opposite
the surface defining the central area and the plurality of annular
rings, or aspherizing the concentric annular ring surface. An
aberroscope or MTF point spread device is preferably utilized to
measure the modulation transfer function of the combination of the
lens and eye.
Obviously, many different embodiments of the present invention are
possible, with alterations of the number of annular rings, the
widths and arrangement of the annular rings, and the optical powers
assigned to each of the annular rings.
While several embodiments and variations of the present invention
for concentric annular ring lens designs for astigmatic presbyopes
are described in detail herein, it should be apparent that the
disclosure and teachings of the present invention will suggest many
alternative designs to those skilled in the art.
* * * * *